Lubricating oil dispersant



United States Patent Ofiice 3,359,204 Patented Dec. 19, 1967 ABSTRACT OFTHE DISCLOSURE The reaction product of a high molecular weight alkenylsuccinic acid or anhydride with a tertiary amine having at least onealkanol and one cyanoalkyl group bonded to nitrogen is an effectiveashless dispersant for lubricating oils.

This application is a continuation-in-part of co-pending applicationSer. No. 387,216, filed Aug. 3, 1964, now abandoned.

This invention relates to oil-soluble lubricating oil dispersants. Inparticular, it relates to the reaction product of high molecular weightalkenyl succinic anhydrides or acids (hereafter termed ASA) withtertiary amines which contain both an a'lkanol and a cyanoalkyl radical.

A large percentage of todays automobiles are used in city stop-and-godriving where the engines do not reach their most etficient operatingtemperatures. Large amounts of partial oxidation products are formed andreach the crankcase of the engine by blowing past the piston rings. Mostof these partial oxidation products are oil insoluble, and tend to formdeposts on various operating parts of engines, resulting in sludge andvarnish. Other deposits and organic acids result from deterioration ofthe oil itself. To prevent deposition of these materials on variousengine parts, it is necessary to incorporate detergents in thelubricating oil compositions, thus keeping these polymeric productshighly dispersed in a condition unfavorable for deposition on metals.

For the most part, the various detergents which have been used toeffectively disperse the precursors of sludges and varnishes are metalorganic compounds, particularly those compounds wherein the metal islinked to an organic group through an oxygen atom. These detergents alsoneutralize to some extent the organic acids, and thereby help preventcorrosion of the engine parts. However, such detergents have thedisadvantage of forming ash deposits in the engine, which deposits lowerengine performance by fouling the spark plugs and valves and bycontributing to preignition.

In recent years, various non-ash producing dispersants have been devisedto overcome these disadvantages. Among such dispersants are imides, forexample, N-dialkylarninoalkyl alkenyl succinimide, produced by thereaction of an alkenyl succinic anhydride and a dialkyl-'aminoalkylamine. Other dispersants are prepared by the reaction of anASA with alkylenepolyamines such as tetraethylenepentamine. A number ofsuch dispersants are disclosed by Norman et al., US. 3,219,666, issuedNov. 23, 1965. These products all have in common the fact that they areprepared from primary or secondary amines which readily enter into amideor imide formations when reacted with ASA. It has now been discoveredthat a very effective class of ashless dispersants can be prepared byreacting an ASA with a specific type of tertiary amine. The tertiaryamine employed must have at least one alkanol substituent and at leastone cyanoalkyl substituent. Dispersants prepared employing this class oftertiary amines not only have excellent dispersing properties, butresult in a lubricant with a reduced tendency to cause corrosion ofmetal engine parts.

Accordingly, an object of this invention is to provide improvedlubricant compositions. A further object is to provide lubricating oilshaving a high degree of dispersancy and low corrosivity.

These and other objects are accomplished by providing an ashlessdispersant which comprises the reaction product of:

(A) one mole part of a succinic acid generating reactant selected fromthe group consisting of alkenyl succinic acid and alkenyl succinicanhydride wherein the alkenyl portion has a molecular weight of from 700to 1600 with (B) from about 0.6 to 3 mole parts of a tertiary aminehaving the formula:

wherein n is an integer from 1-2, m. is an integer from 1-2, the sum ofit plus m is 2-3, R and R are divalent hydrocarbon radicals containing2-5 carbon atoms, and R is an alkyl radical containing from 1 to about18 carbon atoms;

said reaction being carried out at a temperature of from about to 200 C.

In a preferred embodiment the succinic acid generating reactant is anASA wherein the alkenyl radical is derived from the polymerization of amonoolefin containing from 2-5 carbon atoms such that the alkenylradical has a molecular weight of from about 700 to 1600.

In a most preferred embodiment the succinic acid generating reactant isan ASA wherein the alkenyl radical is derived from a polybutene having amolecular weight of from about 800 to 1400 and wherein the tertiaryamine reactant is S-[bis(2-hydroxyethyl)amino] propionitrile.

The alkenyl portion of the ASA is a high molecular weight hydrocarbonradical. It is preferably derived from the polymerization of amonoolefin containing from 2-5 carbon atoms such as ethylene, propylene,butylene, isobutylene, n-pentene, isopentene, and the like. The polymercan have a molecular weight of from about 350 to 2000. In a preferredembodiment the alkenyl radical has a molecular weight of from about 700to 1600. In a most preferred embodiment the alkenyl group is derivedfrom a polybutene having a molecular weight of from about 800 to 1400.Of course, those are understood to be average molecular weights since apolymerization leads to a mixture of polymers which cannot readily beseparated into individual pure compounds. Preferably the polymeremployed in making the ASA has a narrow molecular weight range.

Methods of preparing the alkenyl succinic anhydride or acid are known tothe art. In general, to obtain an alkenyl succinic anhydride, anappropriate polyolefin is reacted with a maleic anhydride. If an alkenylsuccinic acid is desired, the anhydride can be hydrolyzed.

In the following examples all parts are by weight. Example 1 illustratesthe preparation of an alkenyl succinic anhydride in which the alkenylgroup is a polybutene.

EXAMPLE 1 A reaction vessel equipped with heating means, temperaturemeasuring means, stirring means, a reflux condenser, gas inlet andoutlet means and a nitrogen source is flushed with nitrogen and 23.5parts of polybutene having a molecular weight of 1244 and 1.85 parts ofmaleic anhydride are added. The reactants are stirred at 215-220 C. for24 hours, allowed to cool and 11.1

parts of hexane are added. The mixture is allowed to set for aboutseveral hours and is then filtered through Celite via a Buchner funnel.Hexane is stripped from the filtrate at atmospheric pressure at 175 C.and then the pressure is reduced slowly to about 11 mm., holding thetemperature at about 170-180 C. for about one hour, during which timemaleic anhydride is removed. In an average run 10.8 parts of hexane and0.21 part of maleic anhydride are recovered, leaving 22.9 parts ofalkenyl succinic anhydride.

Dilution of the reaction product before filtration can be done withsolvents other than hexane such as benzene, toluene, xylene, etc. It maybe desired to dilute the final ASA-tertiary amine reaction product withoil in order to improve handling properties. If such is the case, thatdiluent can be used in place of hexane in the above preparation of ASA.If an oil diluent is used it is desirable to strip the unreacted maleicanhydride before filtration. A temperature of about 180-185 C. isrecommended if a strip procedure is used because at this temperaturemaleic acid will isomerize to fumaric acid, which is insoluble andreadily removed by filtration.

Some examples of suitable tertiary amines containing both alkanol andcyanoalkyl radicals include 3- [bis 3-hydroxy-n-propyl) amino]propionitrile,

4- [bis (Z-hydroxy-n-propyl) amino] -butyrylnitrile,

2- [bis (2-cyanoethyl) amino] ethanol,

3 [bis Z-cyano-n-propyl) amino] -n-propanol,

N- Zcyanoethyl (N hydroxyethyl (-methylamine,

N- (Z-cyano-n-propyl) -N- 3-hydroxy-n-propyl) laurylamine, and

(S-hydroxy-n-pentyl stearylamine.

The exact nature of the product formed is not known. On first inspectionof the reactants it would appear that simple or polymeric esters of theASA would result since tertiary amines dont form amides. However, withthe specific tertiary amines employed in the present invention theproducts formed are much more complex than this and are best defined bythe procedure used in their preparation.

In preparing the final product it is preferred to use alkenyl succinicanhydride rather than the acid, although the acid can be used. Use ofthe acid results in no savings, but requires an additional hydrolysisstep from the anhydride. Either product will react with the tertiaryamines defined by this invention but the anhydride reacts with theformation of less water, and results in a more desirable product, and sois preferred.

In reacting the ASA with the tertiary amine, the mole ratio of tertiaryamine to ASA is critical to the effectiveness of the final product. ASAsprepared from commercially available polyalkenes generally contain someunreacted polyalkenes. Accordingly, analysis of the ASA prior toreaction to determine its average molecular weight is desirable. Ingeneral, a ratio of from about 0.6 to 3 moles of tertiary amine per moleof ASA can be used. A range of from about 0.75 to 1.2 moles of tertiaryamine per mole of ASA is preferred. A particularly preferred range isfrom 0.9 to 1.1 moles of tertiary amine per mole of ASA. This latterrange yields products with particularly good dispersant characteristicsand with a minimum of corrosive side eflects. At lower ratios than thosegiven, dispersancy of the product is generally unsatisfactory. At higherratios, corrosion problems hecome very serious, resulting, for example,in high hearing weight loss.

The tertiary amine is generally less viscous than the ASA and ispreferably added to a solution of ASA in a solvent. Preferred solventsare hydrocarbons having a boiling point of from about 100-200 C. Morepreferred solvents are the aromatic hydrocarbon solvents within thisboiling range. A most preferred solvent is xylene.

The tertiary amine is generally added to the ASA solution at atemperature on the order of 60-70 C. The mixture is then reacted,preferably under reflux, at from about -200 C. In general, a reactiontemperature of from about -180 C. is preferred. The solvent is chosen toconveniently maintain the reaction under reflux at the desiredtemperature in order to azeo trope with the Water formed during thereaction facilitating the removal of the water. Reaction times aregenerally from about one-half hour to about 8 hours. In most cases, areaction time of from one to 4 hours is sufficient.

Following the above reaction, the temperature can be raised in order toallow removal of solvent and residual Water. The last of the solvent andwater is generally removed by reducing the pressure in the system,causing the solvent to distill out at lower temperatures down to about100 C.

The following example illustrates the reaction of an ASA with thepreferred tertiary amine of this invention. All parts are parts byweight unless otherwise specified.

EXAMPLE 2 A series of eight reactions was conducted according to thefollowing procedure. In each case an ASA prepared as in Example 1 wasadded to a reaction vessel equipped with a stirrer, thermometer, heatingmeans, Dean Stark water trap, condenser and a vacuum pump. In each case,3-[bis(2-hydroxyethyl)amino]propionitrile was employed as the tertiaryamine reactant. Also, xylene was used as a solvent in an amount of aboutone part of xylene for 4.5 parts of ASA. Each reaction differed in themole ratio of ASA to tertiary amine excepting the first two, whichdiffered in the molecular weight of the alkenyl radical on the ASA. Thefollowing table shows the reactant ratio employed in each reaction.

Molecular wt. of Polybuteno in ASA Ratio Product ASA/Amine The reactionswere conducted under a nitrogen atmosphere by warming the ASA-xylenesolution to about 70 C. and then adding the 3-[bis(2-hydroxyethyl)amino]propionitrile. The mixture was then heated to reflux at about -16S" C.The water which codistilled with the xylene was condensed, collected,and removed by way of the Dean Stark separator. The reaction wasconducted for about 3 hours at 160-16S C. and then sufiicient xylene wasdistilled out to allow the temperature to rise to about C. The reactionwas maintained at 180- C. for about an hour. Heating was thendiscontinued and when the product had cooled to about 150 C. thepressure in the system was gradually reduced to about 10 mm., keepingthe temperature of the product at about 110 C. This accomplished theremoval of the last of the xylene solvent. All of the products producedin the above reactions were excellent dispersants.

The products of this invention are quite viscous at room temperature. Adesirable viscosity range for a dispersant is about 300-400 SUS at 100C., and about 10,000 SUS at 160 F. Heating the product before use allowsit to be handled effectively, but preferably the product is diluted withan oil such as a No. 9 refined oil, or other products, for example,Humble SEN-100 or Texaco SEN-'5. The oil may be added to the productafter its formation or it may be added to the ASA prior to the reactionwith the tertiary amine. The preferred method is to add the oil diluentafter the preparation of the final product.

To demonstrate the effectiveness of the products of this inventionvarious representative products were tested in a Fuel Oil DispersancyTest, a CLR-L-38 Polyveriform Test and a Used Oil Sludge DispersancyTest.

Fuel oil discrepancy test This is the Socony-Mobile test described inInd. Eng. Chem, 48, 1892 (1956). One gallon samples of No. 9 refined oilcontaining the additive at a concentration of 25 pounds per 1,000pounds, 1.0 gram of Germantown Bear Lamp'black and ml. of water werecirculated through a 100 mesh strainer for two hours. The sludge depositwas then washed off the strainer, dried and weighed. The effectivenessof an additive is expressed as the percentage reduction in depositweight, referred to as a baseline. When the above test was conductedusing as a dispersant the product prepared in above Example 2 designatedProduct G, the amount of deposit on the screen was reduced 97 percentbelow baseline.

CLR-L-3 8 polyveriform test This is a modification of the 'PolyveriformOxidation Stability Test described in the paper entitled, FactorsCausing Lubricating Oil Deterioration in Engines, Ind. Eng. Chem, Anal.Ed., 17, 302 (1945). See also A Bearing Corrosion Test for LubricatingOils and its Correlation with Engine Performance, Anal. Chem, 21, 737(1949). In thes tests an initially additive-free, 105.5 V.I.solvent-refined SAE-20 crankcase oil was used. The principal conditionsconsisted of passing 48 liters of air per hour through the test oil fora total period of 48 hours while maintaining the oil at a temperature of300 F. Oxidative deterioration of the oil was further promoted byemploying 0.10 weight percent of lead bromide as an oxidation catalyst.Further a copper-lead bearing was submerged in the oil as an additionalcatalyst. To approximate use conditions, 0.08 weight percent zincdithiophospha-te was added. At the end of the test, the loss of weightof the copper lead hearing was determined. (When no loss in weightoccurs a small increase in weight may be observed which can beattributable to the formation of a slight amount of varnish, which is tobe expected from the harsh condition of the test.)

Used Oil dispersancy test In this test, 40 grams of the used oilobtained from the CLR-L-38 Polyveriform Test conducted above arecombined with 60 grams of new oil. The Sludge Dispersancy Test describedabove is then run using this oil; that is, 2 grams of Water andadditional sludge are added. Emulsification and centrifugation are thesame as in that test. A photometer reading is also taken on a blank, themixture of used and new oil prior to running the Sludge DispersancyTest, and the percent transmission obtained from the Sludge DispersancyTest is divided by the percent transmission of the blank to give thefinal used oil dispersion percent transmission value. The results ofthis test as well as of the Polyveriforrn Test described above arelisted.

Product from Bearing wt. Example 2 Percent Light loss (mg.)

Transmission The above tests demonstrate that the present dispersantsnot only impart dispersancy to the oil, but give a nonc-orrosivelubricant.

Other dispersants within the scope of this invention can readily beprepared following the general procedure of Example 2.

EXAMPLE 3 The reaction vessel of Example 2 is flushed with nitrogen and0.5 mole of an ASA derived from a polyethylene having a molecular weightof 600 and 180 ml. of cumene are added. The mixture is heated to 70 C."and 0.5 mole of 6 [(2 hydroxyisopropyl)amino] n capronitrile is quicklyadded. Heating is continued to reflux, about C. Additional cumene isadded to maintain the temperature at about 160 C. for about six hours.Cumene is then distilled oif to allow the temperature to rise to aboutC. and the mixture is held at that temperature for about one hour toremove cumene. The resulting product can be added to lubricating oil todispense sludgeforming materials.

In like manner, good results are obtained using ASAs derived by thepolymerization of other ole-fins such as propylene, isobutylene,n-pentene and isopentene. Likewise, other tertiary amines which containboth a hydroxyalkyl and a cyanoalkyl substituent can be profitablyemployed.

The detergent-dispersants of this invention are effective in bothhydrocarbon and synthetic diester lubricating oils, includinglubricating oils used in spark-ignition engines and diesel enginelubricants. To prepare oil compositions of this invention an appropriatequantity, from about 0.01 to about 10 Weight percent, and preferablyfrom '1 to 5 weight percent, of a detergent-dispersant product of thisinvention is blended with the base oil. Suitable base oils includepetroleum-derived hydrocarbon mineral oils and also synthetic diesteroils, such as sebacates, adipates, silicones, halogen containing organiccompounds including the fluorocarbons, etc, polyalkylene glycollubricants and organic phosphites which are suitable as lubricants.

EXAMPLE 4 Product from Example 2: Cone (wt. percent) A 0.01 B 0.1 C l D2 E 5 F 7 G 10 EXAMPLE 5 Lubricating oils are prepared as in Example 4by blending the listed oil with the products prepared in Example 2. (A)A dioctyl sebacate having a viscosity at 210 F. of

36.7 SUS, a viscosity index of 159 and a molecular weight of 426.7.

(B) A di-(sec-amyl) sebacate having a viscosity at 210 F. of 33.8 SUS, aviscosity index of 133 and a molecular weight of 342.5.

(C) A di-(Z-ethylhexyl) sebacate having a viscosity at 210 F. of 37.3SUS, a viscosity index of 152 and a molecular weight of 426.7.

(D) A di-(2-ethylhexyl) adipate having a viscosity at 210 F. of 34.2SUS, a viscosity index of 121 and a molecular weight of 370.6.

(E) A diisooctyl azelate having a kinematic viscosity of 3.34centistokes at 65 R, an ASTM slope from-40 F. to 210 F. of 0.693, a pourpoint of -85 F., a flash 7 point of 425 F. and a specific gravity at 25F. of 0.9123. (F) A diisooctyl adipate having a viscosity at 210 F. of35.4 SUS, a viscosity at 100 F. of 57.3 SUS, a viscosity of 3,980 SUS at40 F. and a viscosity index of 143.

I claim:

1. An ashless lubricant dispersant comprising the reaction product of:

(A) one mole part of a succinic acid generating reactant selected fromthe group consisting of alkenyl succinic acid and alkenyl succinicanhydride wherein the alkenyl portion has a molecular weight of from 700to 1600 with (B) from about 0.6 to 3 mole parts of a tertiary aminehaving the formula:

wherein n is an integer from 1-2, m is an integer from 1-2, the sum of nplus in is 2-3, R and R are divalent hydrocarbon radicals containing 2-5carbon atoms, and R is an alkyl radical containing from 1 to about 18carbon atoms; said reaction being carried out at a temperature of fromabout 100 to 200 C.

2. The composition of claim 1 wherein said succinic acid generatinggroup is an alkenyl succinic anhydride wherein the alkenyl radical isderived from the polymerization of a monoolefin containing 25 carbonatoms such that said alkenyl radical has a molecular weight of fromabout 700 to 1600.

3. The composition of claim 2 wherein said alkenyl radical is derivedfrom a polybutene having a molecular Weight of from 800 to 1400 andwherein said tertiary amine is3-[bis(2-hydroxyethyl)amino1propionitrile.

4. A lubricating oil containing a dispersant amount of the compositionof claim 1.

5. A lubricating oil containing from 0.01 to 10 weight percent of thecomposition of claim 2.

6. A hydrocarbon lubricating oil containing from 0.01 to about 10 weightpercent of the composition of claim 3.

References Cited UNITED STATES PATENTS 3,219,666 11/1965 Norman et al.252-515 3,272,746 9/1966 Le Suer et a1. 252-51.5

DANIEL E. WYMAN, Primary Examiner.

PATRICK P. GARVIN, Examiner.

1. AN ASHLESS LUBRICANT DISPERSANT COMPRISING THE REACTION PRODUCT OF:(A) ONE MOLE PART OF A SUCCINIC ACID GENERATING REACTANT SELECTED FROMTHE GROUP CONSISTING OF ALKENYL SUCCINIC ACID AND ALKENYL SUCCINICANHYDRIDGE WHEREIN THE ALKENYL PORTION HAS A MOLECULAR WEIGHT OF FROM700 TO 1600 WITH (B) FROM ABOUT 0.6 TO 3 MOLE PARTS OF A TERTIARY AMINEHAVING THE FORMULA:
 4. A LUBRICATING OIL CONTAINING A DISPERSANT AMOUNTOF THE COMPOSITION OF CLAIM 1.